/ Home & Energy

Have you ever had a DIY disaster?

Are you embarking on a DIY job this bank holiday weekend? Perhaps you’ve already started but have bitten off more than you can chew? You wouldn’t be alone, new Which? research shows…

Our new research today shows that many of us take on DIY jobs that are actually beyond our capabilities – with over half of Which? Trusted traders surveyed, reporting being called in to fix jobs that have gone so badly wrong that they’re potentially dangerous.

Plumbing jobs are the most commonly abandoned by DIYers, as one plumber said: ‘As soon as water starts leaking, people will call in a professional.’

Sometimes jobs can turn out to be more complicated than DIYers expect – you often can’t see the extent of a problem until you start trying to fix it. Although some people simply shouldn’t be trusted with a tool kit.

Home improvement

I fall into the unskilled DIYer category. My husband has banned me from DIY home improvements, as my efforts don’t match up to his high standards. I’m letting down the sisterhood but I fear it may be in the genes.

My late father, despite being a remarkable man in many ways, had little talent for DIY. He wouldn’t mind me sharing the story of his most famous DIY failure – my sister’s Sindy House. Sindy was the UK version of Barbie, and had a range of accessories that were hugely popular in the 1980s, when we were small.

The Sindy House was designed to stand over a metre tall, with four floors and several different rooms. It came flat-packed, with multiple tiny pieces and – according to my father – incomprehensible instructions. After a lot of swearing, he managed to construct something structurally unsound, which listed like the leaning tower of Pisa.

Luckily for my sister and her Sindy dolls, there were professional builders working in our home at the time. So my father called the builders away from their actual job, and got all three of them working on the Sindy House instead.

He salvaged some pride from the fact they found its construction tricky, too – when telling the tale, his final line was always ‘…and it took them three hours to build the b***** thing!’

I’ve no idea what they charged but they did a good job, as our Sindy House stood tall for years.

Have you started a DIY project only to have to call in a professional to finish it? Or maybe you’re a home improvement whizz – what DIY project are you most proud of?


I am a DIY enthusiast and will have a go at all sorts of small repair jobs but have never tackled anything major, although I did once rebuild the engine of my first car after it had failed rather spectacularly. When the RAC chap asked me where I wanted the car towed to, I gave my parents’ address, 40 miles away, when the more sensible answer would have been to find a garage.

Focusing on smaller jobs, there are not many occasions when I have been in the position of wishing I had not started a job, but a plumbing incident comes to mind. Not long after I had moved into my present house I noticed a small damp patch on the floor of the airing cupboard one evening. It looked as if one of the seven gate valves had a slight leak so I found a shallow container to catch any more drips until I could investigate the following morning.

Stupidly I decided to take action that evening rather than waiting until the following morning, assuming that tightening the gland nut would do the trick. As soon as I applied a spanner, a small jet of water issued from the side of the valve and I had to hang a cloth over it to direct the water into my container. Further efforts with the spanner reduced the flow but I could not stop it. There was no room for a bucket under the leak, so I turned off the water at the mains but that made no difference because there was a full hot water tank. At 9pm it was a bit late to knock on the door of neighbours, who I did not really know at that time, so I headed for the village pub to ask about local plumbers. No joy, so I went home and decided that the job could wait until the morning if I got up every two hours to empty the container. In the morning I drained the system and went to the recently opened Screwfix to buy a replacement gate valve. The lesson learned was not to embark on any plumbing jobs in the evening.

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Engineering requires a mathematically astute personality. There’s a similar issue with STEM subjects and the performance of boys in education has been a worrying aspect of 21st Education in general. Boys have been largely out-performed by girls since the mid ’80s, and no one’s entirely sure why.

As far as DIY goes, I’m not sure that formal education is much of a benefit. We tend to pick up skills by trial and error, by working together and by discussion of problems and achievements with others. Much of what I have learned has been from three civil servants, including my late father, who were extremely practical.

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One skill where formal education helped me (local nightschool) was in bricklaying. First was the logical order of build – set up stepped corners first, very carefully with the level and plumb – before infilling. Second was to use a mortar of creamy consistency – more fluid than I would have tried – and place the brick with as little meddling as possible against the string line. Let the mortar that squidges out of the joints firm up before attempting to neaten it; then cut it off with the trowel and shape and smooth the joint. This avoids staining the brick surface with wet mortar.

I expect plastering would also require tuition, something I have never attempted other than patching.

From the Economist
Why are girls performing better at school than their male classmates?

First, girls read more than boys. Reading proficiency is the basis upon which all other learning is built. When boys don’t do well at reading, their performance in other school subjects suffers too.

Second, girls spend more time on homework. On average, girls spend five and a half hours per week doing homework while boys spend a little less than four and a half hours. Researchers suggest that doing homework set by teachers is linked to better performance in maths, reading and science. Boys, it appears, spend more of their free time in the virtual world; they are 17% more likely to play collaborative online games than girls every day. They also use the internet more.

Third, peer pressure plays a role. A lot of boys decide early on that they are just too cool for school which means they’re more likely to be rowdy in class. Teachers mark them down for this. In anonymous tests, boys perform better. In fact, the gender gap in reading drops by a third when teachers don’t know the gender of the pupil they are marking.

More on topic:
With new research out (April 2014) it states 60% of women say they are more likely to be carrying out home improvements than their partners.
http://www.dailymail.co.uk/femail/article-2609369/Sisters-doing-Now-60-women-say-theyre-charge-DIY-mens-practical-skills-decline.html so it must be true.

The Economist article is just rather meaningless words, and gives no real insights as to why this is all happening. We do know boys don’t embrace delayed gratification, which girls seem to be able to, but we don’t know why, or why boys don’t read as well as girls, or why boys don’t spend more time on homework, or why girls prefer detailed work.

A good example of words as opposed to meaning is this sentence: “A lot of boys decide early on that they are just too cool for school which means they’re more likely to be rowdy in class”, which really takes the biscuit for meaningless and unsubstantiated drivel.

It’s true boys are more physically inclined than girls, and so making them sit quietly when thousands of years of evolution are telling them to do precisely the opposite could be a factor in poor class discipline.

But we do need to address some of the other factors and, while we’re at it, examine why those boys who do do well often excel over girls in examinations. But the short answer is that we don’t know for sure why this has been happening for around 40 years, or how to change it, a[art from the obvious one of making boys enjoy knowledge. And that’s down to parents, whose influence during the first five years of life exceeds all others.

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That’s not the point, Duncan. The issue is we don’t know why the performance of boys in the education system has declined in relation to that of girls over a 40 year period. There are many ideas and numerous opinions, of course, but we don’t fully understand why it’s happened. And I don’t know why you quote ‘mystery to me; I never said there was a mystery. You’re the only one who’s used the word, in fact.

Finland routinely tops rankings of global education systems and is famous for having no banding systems — all pupils, regardless of ability, are taught in the same classes. As a result, the gap between the weakest and the strongest pupils is the smallest in the world. Finnish schools also give relatively little homework and have only one mandatory test at age 16.*1

But throughout the world females are routinely disadvantaged in education, many being excluded from it completely. However, that’s changing, and although numerous studies show the positive effects that female teachers can have on girls’ learning, world-wide boys are leaving education earlier than girls.*2

It’s far from a simple picture, but the UK and US are nowhere near the top in the World education rankings.

*1 Independent.
*2 UNESCO eAtlas of gender Equality

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I’m not at all clear who we might regard as the “greatest minds in this country“.
What evidence do you have to support the assertion that “female teachers just aren’t willing to either accept nor understand the male mentality”. On the latter point, the way differences between sexes is heading, I’d have thought there was more chance now of cross-understanding than there has ever been.

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…and in answer to your first questions, Duncan, (How come all this “we dont know ” started up in recent decades when this wasn’t an issue in the past) the fact is that it’s always been an issue. And your making wild assertions you cannot substantiate simply devalues your argument.

duncan, there is a difference between personal experience, and a generalisation. I was not challenging what you went through but extending that experience to everyone.

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It’s utterly wrong on the two main points you’re making. Apprenticeships for the less-academically inclined started to become a thing of the past in the ’80s; they were almost non-existent by the end of that decade, and it had nothing to do with your female fixation, but rather the economic policies under the Thatcher regime. Even when they were freely available the competition to actually get a decent one was fierce, so young men could not always get an apprenticeship.

[Hi Ian, your comment has been edited. This is because the comment a) we’ve edited the comment you’re replying to so the context has been lost, b) we need to be careful when making reference to mental health issues. https://conversation.which.co.uk/commenting-guidelines/. Thanks, mods.]

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I’ve had to edit quite a few comments in this thread. The thread has become very off-topic in many parts.

Some of the comments made were reported as being offensive, and as such, I have edited them where appropriate. Please be careful when making generalisations, because these can be offensive to others.

Can I also ask that you are careful when discussing mental health issues? I know that no one would intend to offend on this subject. We want Which? Conversation to be an open and welcoming place. If anybody has any comments or concerns about mental health, which relate to consumer issues, I would kindly ask that you get in touch with us directly. Alternatively, if on-topic (and appropriate), please make comments on this subject welcoming and constructive.

We also recommend, for anyone who may suffer with suicidal thoughts, to get in touch with the Samaritans: https://www.samaritans.org/

Thank you.

Two diy disasters were down to lack of forethought and knowledge.

When beginning conversion work on a bungalow a bedroom chimney had to be removed, so I started with the fireplace. A surround of small local bricks went first – saved those for reuse – and then the shaped fireback. That came out surprisingly easily, and I lifted it with two hands to get it out of the way. The lack of knowledge then kicked in when learned that the fireback was made in two equally heavy halves, upper and lower, joined with asbestos rope and soot. The lower part detected when it was passing over my feet and declared independence. My trainers offered no protection and I spent the rest of the day on the sofa.

The other involved an old B&D (orange and silver) electric drill with a slightly temperamental trigger switch. I was making a new fitted kitchen and had completed the sink unit framework. A long hole was needed through the outer brick wall so I was inside this wooden cage when the drill bit got stuck. I switched off the drill, but the switch chose to stick. If I let go of the drill it would spin out of control, too close for comfort, and if I did nothing the drill would no doubt burn out. The plug was in a socket well out of reach. It seemed to take a while for presence of mind to operate, but when it did a sharp tug on the lead came to the rescue.

DiY is a lot about trying, making mistakes, not repeating them – and reading books. I had the Readers Digest DIY Manual – loose leaf, grey plastic binder – that gave really useful and practical information on almost everything.It encouraged me to tackle lots of jobs I would have have hesitated over otherwise.

That Readers’ Digest loose leaf book was a Godsend when I first got married. I was pretty much ok, but it was great to know that was on the bookshelf – wedding present from a thoughtful father.

Yes, I’ve just been a clot. Dirt in the mower carburettor so I took a spanner to the engine and dismantled a lot of bits. Fool mistake one: no replacement gaskets. Fool error two, I placed a part out of sight and forgot to replace it. The upshot was that the carburettor was loose and I didn’t know why. Tightening it up with a spanner stripped the thread in the engine block -end of story. I might have been more upset, but the mower was about fifteen years old. When the new one came out of its box, I couldn’t find a throttle control. After an hour of harsh words and wondering whether to return it to the shop, I found that there isn’t one on some mowers. You start it, mow and stop it. The motor just revs as it wants. Very strange. These days ladders scare me more than they did, but I’m getting to be an expert with a chain saw. Gone are the days when fitting a new gearbox was an afternoon under the car with a jack, though my power tool has some good old fashioned grease nipples so my trusty gun has found a new life after forty years in the tool box. I don’t mind plumbing so long as I know where the various valves are. I use compression joints, not blow torches. Anything major gets paid for these days. time is pressing and there’s always too much to do.

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It is strange when every useful but taboo word I ever learned is now broadcast on radio and tv, printed by the press, published in books, and yet we have some stupid censoring system living in the past and that is not intelligent enough to learn the meanings of words, particularly in context. It all seems to be a bit of a c**k eyed world these days,

There are ‘reserved words’ that have been selected to be asterisked out by a person in Which?; I suspect ‘s c r e w i n g’ is one such but in fact,given that some of us are more than happy to report any deviant posts, I would say that most of those sorts of terms should be removed from the reserved list.

I don’t know if thread inserts are available for small bolts, but surely the easiest solution is to tap a new thread and use a larger bolt, assuming that there is enough metal. A DIY disaster then becomes an effective repair.

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That’s why I said ‘assuming there is enough metal’. I appreciate the problem you mention and that’s why it’s so important to avoid stripping threads.

A larger screw or bolt might not suit the attachment. We used Helicoil inserts to provide a thread in unsuitable materials but these require the right kit. Not the sort of thing a diyer would have. Maybe best to take it to a garage or local engineer for them to fix. It is always a challenge to fix things yourself but sometimes best to admit defeat.

I’ve not encountered a problem so far and like my father I do not like admitting defeat. I don’t have any Helicoils or equivalent but I know an agricultural engineer who has thread inserts and the taps needed and is happy to lend me tools and offer advice. I have given him advice and help with other things.

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One of the reasons we have to do repairs is because manufacturers have used inappropriate materials, as with your belt buckles. My expensive laser printer would print a few pages but would jam on longer print runs because the rubber rollers had deteriorated as a result of heat from the fuser unit. I made silicone rubber rollers and this cured the problem. Some of my DIY repairs have involved replacing broken plastic parts with metal. One of the most useful techniques I have learned is how to silver solder. For me, the challenge of doing repairs is the most enjoyable type of DIY.

And the silly thing is if you really want to get round this, just add a space to your scre wing and c ock eyed world.

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A few DIY tasks are simple but can go horribly wrong if not done correctly. After my father died, my mother decided to bleed the radiator in my bedroom because I was coming home for the weekend. She was in her late 70s and knew the purpose of bleeding radiators but my father or I had taken care of the job in the past. The small brass screw came out and landed in an inaccessible place between the bedroom wall and a heavy piece of furniture. There was no room to place a bucket to collect the hot water coming out of the radiator. There was no valve at the other end of the radiator and even if there had been my mother would probably not have known how to close a lockshield valve. It was a couple of hours before an emergency plumber arrived and as a result of the flood, two rooms needed to be redecorated and two carpets replaced.

All this hassle because whoever had designed the radiator vent had not thought to make the screw captive.

Radiator bleed screws are not captive, in my experience, but do not need undoing much for them to release air (and water). It is important to locate a radiator, or arrange furniture, to get access to bleed it, and to be able to comfortably hold a container at the outlet to catch the escaping hot water.

It is always sensible, I would suggest, to have a valve at each end of the radiator so it can be isolated – for replacement if it leaks or for removal for flushing if it gets a little clogged. Radiators, or at least their valves, may be in places that are not quickly accessible and it may not be immediately obvious how to close the lockshield. Doing these jobs does require a basic understanding.

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Malcolm – I’m aware of the precautions and have both fitted and replaced lockshield valves. The problem arose because the pump had to be switched off, otherwise opening the bleed valve would allow more air to enter, as Duncan has explained. My father and I knew this but my mother just assumed that she had not loosened the valve enough. I don’t know how common this problem is but it could be avoided by better design – a captive bleed screw.

With some radiators it is possible to fit an automatic bleed valve. Air can pass through a dry felt pad but when this gets wet the surface tension of water prevents leakage. I used to have one on my hall radiator – the only one that ever needed attention – and it worked very well.

I used to bleed my radiators annually as a matter of course, until I realised I only needed to check whether the heat was consistent from top to bottom, which strangely it always is, so now I don’t bother to do them unless they are only partially hot.

My DIY skills are usually limited to a brush and a tin of paint, and a thread is a piece of cotton you push through a needle to sew or repair a piece of material. A screw Duncan, I thought was a Victorian jailer whose job it was to entice you into turning a handle that was tightened at various intervals to punish you for past misdeeds 🙂

I usually manage to put together a flat pack after first glancing at the usual inadequate instructions, tossing them aside, and then resorting to the same logic I used before the days of TV when jig-saw puzzles were a constructive and pleasurable way to pass the time.

A couple of weeks ago however, I decided it was time to tidy up the garden but couldn’t open the shed door as the handle failed to turn owing to a missing screw. After much huffing and puffing I decided to abandon the gardening until the following day. It was the thought of paying a locksmith £80 + that prompted me to reach for the WD40 and managed to prise the door open and squirt it in every accessible orifice! A quick search for an appropriate sized screwdriver and screw and the job was completed and the garden tools were once again accessible.

I did manage to erect two fence panels and posts myself about 15 years ago, but wouldn’t attempt it now, so have arranged to pay someone to replace the whole original fence within the next few weeks.

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WD40 and similar products are great for removing rusted screws and may other things that need to be released, but they evaporate and it’s necessary to use oil or grease to ensure that the problem does not happen again.

If radiators have a cold area in the middle at the bottom this is sure sign of a build-up of iron oxide sludge, resulting from serious corrosion of the steel. Corrosion inhibitors are very good at preventing this happening and can avoid problems including radiator leakage. It is essential to replace the inhibitor if the system is drained to carry out work.

One of my hated DIY jobs was applying creosote on garden fences. I am not surprised that it is no longer sold to the public because it’s a cocktail of hazardous chemicals. Most of the fence treatments seem to be no more than paint and offer no protection against growth algae or rot. Presumably the best bet is to buy pressure-treated timber and use fence treatment if you want to change the colour.

Thanks Duncan, thats a very useful tip.

Another tip on the turning handle…. find a screwdriver that fits corner-to-corner in the square drive of such latches. If the problem occurs in future, take out the square drive and temporarily insert the screwdriver in the square hole. This can usefully overcome even worn locks to get you out of trouble – as most latches are two-way (but the pull-down handles only get used one way).

I presume that’s why flat-bladed screwdrivers with tapered ends (cabinetmaker’s?) were invented.

The problem was I had painted over the shed door knob plus the two screws on each side some time ago when I repainted the shed and couldn’t shift the remaining screw with an ordinary screwdriver. When I finally managed to open the door I was able to remove the inside knob and gain access to the latch and its component parts.

I will try to remember to replace the WD40 with machine oil, thanks Wavechange.

A tip for wrought iron bird feeders that are beginning to look a bit jaded and rusty around the wing screws is to first remove the food and water dishes and rub it down with WD40 sprayed onto a cloth or a piece of kitchen paper. I have recently treated mine and it looks brand new again.

I guess we have all struggled with painted screws. Pozidrive screws may be easier to use than slotted ones, but not when you have to remove ones that have been painted.

WD40 and similar products have many uses you might not think of, as does Brasso and other polishes.

I just tie my bird feeders to a lilac tree, but the metal ones are going rusty. I’m not keen to spray them with anything that could harm the birds. The plastic feeder has other problems. I would like to find stainless steel feeders that won’t go rusty and will last a few years.


As far as I know cabinet screwdrivers do not necessarily have tapered ends. Those I have possess oval wood handles that make turning easier. Nice tools to use.

OK, a flared screwdriver, but I’ve often heard them referred to as cabinetmakers screwdrivers.

I’ll go for the ones without tapered ends, especially since I prefer Pozidrive screws.

While we’re talking “gotchas” on removing rads, don’t rely on the thermostatic valve turned fully off to hold back the water in the winter – a sharp cold night can cause a stub pipe to cool to the point that it opens up to prevent pipe freeze – with a mini flood in the morning! It is easily solved with a service cap – or if not available, a penny piece over the plunger and **gently** retightening the TRV on top to compress the pin irrespective of what the stat calls for.

Are you speaking from experience, Roger? 🙂 It’s worth making sure that the plunger moves easily because if it sticks in the radiator will stay cold or not get very warm. Turning TRVs from maximum to minimum settings occasionally may prevent them becoming stuck.

🙂 Yes experience of providing a penny to one who had the problem who was using a decent book to hold the plunger in with his posterior on the book! Fortunately the carpet had been stripped and the floor was tounge and groove over devegetated earth – I whipped up a board and swept the few gallons away before anything of note was absorbed anywhere it mattered.

I have had to give a few of them a bo11ocking (another good old engineering term) with WD40 every few years!

Only had one real disaster, drilling through a mains cable in the wall. Forgot when the kitchen was revamped that one of the sockets had been moved but the original cable was still there. What fascinated me though, apart from my own stupidity and the little jet of flame that shot out of the hole, was that my lovely shiny electric drill chuck and bit immediately went rusty, no idea why.

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Cables should be run vertically in walls but that does not always happen. It’s worth turning off all power at the distribution board and using a battery-operated hammer drill, even if you have to borrow one. You might still drill a cable but at least it will avoid watching a brief fireworks display.

Decent cable detectors may be available but those I have used were not to be trusted.

Cheap cable detectors often don’t penetrate far. My son hit a water pipe in his bathroom despite using a detector – it was in the wall behind plasterboard on battens.

The rust on your drill bit might well have been vapourised copper deposited when you hit the live conductor.

It is wise to isolate the lights and sockets at the distribution board before drilling or putting in a picture hook nail. However you will not know whether you have damaged any wiring until you turn the power back on – and not even then if it has not shorted. So your picture hook might end up live.

Best to invest in a decent detector as it could save a lot of money. Something Which? could do test on perhaps? Seems simple enough to test. One list on line here:https://www.tektouch.net/tools/best-live-cable-detectors.php#BosGMS1

I’d forgotten my one of those – putting in a panel pin as a picture hook. The lights went out. Almost uneventful though. The wire was in a shallow metal conduit – and it just popped the earth leakage trip. I am guessing I hit the neutral or (unlive) switched live. When I took the panel pin out I could see nothing of any significance on it, and when I reset the trip it stayed fired. I deduced that the worst I had was a tiny hole of no consequence through two insulator sleeves inside a conduit. That was three houses ago and I expect it is still working!

Short circuiting the Earth and Neutral will trip the RCD even if the power is switched off. I was reminded of this last year when installing additional lighting in my garage/workshop. This seems likely if there were no sparks and the panel pin was undamaged.

I once had a near disaster. I was replacing a mains socket in my parents’ large garage and if I had turned off all the power I would not have been able to see what I was doing. Instead, I removed the relevant fuse and used a neon tester to confirm the power was off. I proceeded to replace the socket and then discovered I had removed the wrong fuse and that the neon tester – which had worked for years – was faulty. I had not received even a tingle, but now I always check that neon testers work before using them and if possible turn off everything and use battery-powered lighting.

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Of course. In my case the reason I did not even have a tingle was that I did not touch the wires. It was about 40 years ago and made me more careful Since then I have discovered several neon testers that have either failed or not been reliable.

A good test for a socket is a portable lamp. Best to have RCCD protection but I’d never rely on it; physical disconnection is best, like removing the fuse, as wavechange did, or switching off the MCB. And check. You are still trusting whoever wired the socket connected line and neutral properly at the board. If in doubt use the main switch.

After my incident I made a home-made socket tester that sockets are wired correctly. When I rented a flat it alerted me to the fact that there was no Earth connection on the socket for the electric fire in the lounge. I now use a Martindale tester because it gives an indication of whether the Earth connection is inadequate without tripping the RCD:

Credit: Martindale

I believe that similar testers that check Earth impedance are now available from other manufacturers. Testing with socket with a lamp won’t show if L and N have been connected the wrong way round or if there is a satisfactory Earth connection. Extension cables often have poor Earth connections and I’ve found two that were cross-wired L to N.

That is far better than the simple neon one I carry – where a wet string between neutral and earth would likely be sufficient to get a “good” result!

That’s the problem. My home-made socket tester and most of the ones on sale are little better if there is a poor Earth. I once gave one of these socket testers as a Christmas present to a DIY enthusiast who had (almost) everything.

I’ve been wondering how such a device would work without causing an RCD to trip. I think if I were to design one it would have to have some intelligent circuitry and a couple of GTO thyristors to add a high current (well relatively, probably under an amp) pulse up the earth lead for only a few microseconds from rectified mains to avoid tripping the trip and measuring the delta V using sample and holds – probably once every few seconds. In fact by doing that alternately using the Live as a “reference terminal”, you could assess the relative impedance of the N and E and so determine whether they were swapped over. Patentable?

I wondered the same, Roger, but it does work, at least with a standard 30mA RCD. It sometimes trips a 10mA RCD, as I discovered when using an outdoor power socket.

You won’t be able to patent your ideas because they have now been published. 🙁 I would not mind taking one apart and seeing what is inside. There was a recall on the EZ150 because some had not been properly glued together, but neither of mine came apart.

I am sure by now the market for this is nailed – but I did record – and have witnessed – the basic claim in my book before writing it on here – so I likely still would be able to get it patented…

Unfortunately, until you have filed a claim for consideration by a Patent Office, prior disclosure will invalidate it in most countries – including the UK and most of Europe. Some countries give grace periods of up to 12 months.

Malcolm has beaten me, but I was asked to temporarily withdraw a journal article prior to publication because a patent chap at the company I was working with told me that it would invalidate the patent.

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I’m not suggesting that a plug-in tester is a substitute for a proper tester, Duncan. Few DIY users have equipment to test Earth-loop impedance. I used to borrow a PAT tester from work, mainly to check earthed products such as kettles. Now I use an ancient Metrohm that measures to less than 0.05 ohms.

These testers are good to establish earth impedance of appliances, but unless you can connect to “real” earth with a second probe, how do you tell the impedance of your earth house wiring? Answer: inject a current into it from somewhere and measure the voltage change when you do so – qv my thought above needing no additional connection to real earth.
Refinement – would need a zero crossing detector and do the few µs current pulse and control measurements at the same point in each mains cycle. Still think it’s worth a play. Might even knock one up in the winter.

At the end of my first year at university a friend of my father found me a job with a small company that repaired and calibrated electrical/electronic test equipment including line earth impedance testers. I remember the boss explaining this and me installing a test facility of known impedance to check calibration. I was paid £5 a week to play with all sorts of fancy test equipment and would gladly have paid more for the experience.

We might be off the topic of DIY disasters but I’m certainly interested in your ideas.

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I really think it may have legs having thought about it from cold after a snooze.
For PME and across the pond, yes a separate earth reference would be needed – but not for UK if we can (effectively) use Live when crossing zero as a DC reference.
And it’s well on topic if I choose the wrong thyristor – a DIY disaster in the making lol

I do struggle to understand the merits of different earthing systems. I assume that having a low impedance is less important when an RCD is present. Having said that, a higher than expected reading should be investigated because a dodgy connection could fail.

I like the humour in your final sentence, Roger.

One of my very first projects at work in 1978 – I forget the exact details – but it involved a very low current/low voltage feed from rectified mains to do something for a short whle. This predated VFETS of course. I rigged up a simple circuit – all ratings thoroughly checked on the pass transistor…. BANG – out went a few fuses.
That was my baptism of fire into the safe operating area of bipolar transistors in conduction!

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I do enjoy the discussion of electronics though my soldering iron is not often wielded these days. I wonder if our non-technical readers might think a bipolar transistor might need treatment for depression.

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It may need a shot of lithium, or failing that. sodium valproate Wavechange 🙂

I know, Beryl. One of my friends at university worked with people with serious problems. Our bipolar transistors will respond to a lithium-ion battery, if it’s corrected the right way round.

This was a joint near disaster when I was building a brick double garage with a builder friend (and a good builder from the old school). We’d laid about 3 courses on the section of one side before we realised we hadn’t continued with the damp proof membrane. The mortar was still fresh so we just removed all the affected bricks and did it properly. We’d have been much more upset if the wall had been finished before we found out.

It is worth reading this before embarking on a diy project. Otherwise another disaster might be in the making.